Variable rate spring assembly



March 25,

Filed Dec. 3

1952 A s. KRoTzv 2,590,711

VARIABLERATE SPRING ASSEMBLY 2 SHEETS-SHEET 1 March 25, 1952 A, 5f KROTZ l 2,590,711

VARIABLE'RATE ,SPRING ASSEMBLY Filed Dec- 3l, 1946 2 SHEETS-SHEET 2.

Patented Mar. 25, 1952 VARIABLE RATE SPRING ASSEMBLY Alvin S. Krotz, Akron, Ohio, assignor to The B. F. Goodrich Company, New York, N. Y., a corporation of New York Application December 31, 1946, Serial No. 719,446

3 Claims. 1

This invention relates to spring assemblies and especially to vehicle suspensions. Many of the vehicles currently in operation carry loads of different weights. For cushioning of the light loads a soft springing action is desirable and for cushioning of the heavier loads a stiffer springing action is desirable. A spring assembly which would provide such a variable rate of springing action would nd a wide application in suspensions for load-carrying vehicles such as freight trucks which often carry heavy loads to a point and return with light loads.

Objects of the invention are to provide an improved spring assembly that will be eiective under the conditions discussed above; to provide a soft springing action for light suspended loads and a stiffer springing action for heavy suspended loads; to provide for adjustability of spring stiffness; to provide for quietness of operation; to provide absorption of shock and impact in all directions; to eliminate the necessity for lubrication; to provide lightness of structure and to provide for convenience of construction and installation.

More specific objects are to provide a plurality of bodies of rubber-like material with a connecting structure to attain the foregoing objects; to provide cushioning of the vehicle by stressing the bodies in torsional shear; to provide apparatus for engaging the bodies to stress them together in torsional shear and to provide apparatus for limiting the stress on the bodies.

These and other objects will be apparent from the following description, reference being had to the accompanying drawings in which:

Fig. l is a plan view of a vehicle suspension constructed in accordance with and embodying the invention, parts being broken away.

Fig. 2 is an elevation of the suspension shown in Fig. 1.

Fig. 3 is a section taken along line 3-3 of Fig. 2, parts being sectioned and broken away.

Fig. 4 is asection taken along line 4--4 of Fig. 3.

Fig. 5 is a section like Fig. 4 showing the pcsition of the suspension lwith the shaft sections in working engagement.

Fig. 6 is a plan viewv of a modied construction, parts being broken away.

Fig. 7 is a section taken along line I-l of Fig. 6.

Fig. 8 is a plan view of a further modification. parts being .broken away.

A vehicle suspension incorporating a spring assembly constructed in accordance with and embodying the invention is shown in Fig. 1 `in which the vehicle has a chassis which comprises longitudinal members II and transverse members I2. A bracket member I3 is mounted on the transverse member I2 and disposed in such a position that a spring assembly may be mounted between the bracket and the longitudinal member II in a position transverse of the chassis. The bracket I3 and the longitudinal member il have co-axial apertures Ic, IB in which shafts I4 and 2l! respectively are disposed in end to end alignment. The abutting ends of the shafts 2li and I4 have inter-engaging teeth i5 disposed in a lost-motion connection in a manner such that limited relative rotation of the shafts 2B and I4 is permitted.

A sleeve I5 is disposed about each shaft I4 and 29 and an annular elastic body of resilient rubber-like material I1 is interposed between and bonded by suitable means such as vulcanization to the shaft and sleeve. Each sleeve I6 is mounted xedly in a shell I8 which is mounted rotatably in the apertures I0, le in the longitudinal member Il or in the bracket member I3.l The shell member I8 has a ring member I9 mounted xedly thereto at the outer circumference.

Adjusting ring members 2| and shim members 22 are mounted between the ring members I9 and the bracket I3 and the longitudinal member Il. The shim members 22 are disposed in such a manner as to prevent axial movement of the spring assembly. Studs 23 are mounted xedly in the shim members 22 and disposed in apertures in the ring member 2l and adjusting member I9 to prevent relative rotary movement of the members. Each adjusting ring member 2l has a projection 24 extending radially from the ring member. A pin 25 is mounted on the projection 24 and a threaded adjusting stud 26 is mounted rotatably on the pin and extends through an aperture in the transverse member I2. A nut 21 is threaded on the adjusting stud 28 to restrict movement of the stud relative to the transverse member i2.

The portion of the shaft IllV adjacent the bracket I3 has a lug 28 projecting radially from the shaft to restrict rotation of the shaft by engagement with a bolt 29 which extends into'the path of rotation of the lug 28 and is threaded in a channel member 3l mounted on the transverse member I2.

A disk member 32 is inserted in the end of the shaft portion 2Q adjacent the longitudinal member IIr and mounted xedly thereto. One end of an arm 33 is mounted on the disk member 32 by studs 34. The other end of the arm 33 is mounted on Van axle housing 35 which encases an axle 38 upon which a wheel 31 of the vehicle is mounted. The suspension is shown for one wheel, however, the other wheels of the vehicle may be similarly mounted.

In operation, as weight is added to the chassis the arm 33 will tend to turn in a counter-clockwise direction as shown in Fig. 2 which will urge the shaft 20 adjacent the longitudinal member II in a counter-clockwise direction. The sleeve I6 and the shell I8 adjacent the longitudinal member H are prevented from turning by the adjusting ring member 2| which is secured to the transverse member I2 by the adjusting stud 26. The relative rotary movement of the shafts 20 and I4 and the shell I6 will stress the body of rubber-like material I1 in torsional shear which will cushion the vehicle. I

During the initial deection of the body of rubber-like material I1 adjacent the longitudinal member II the shaft 20 adjacent the ybracket I3 will not be affected as the space between the teeth I of the shafts I4 and 20 will permit relative rotary movement of the shafts. When a load has been applied to the vehicle which will cause the body of rubber-like material to deflect sufficiently, the teeth I5 of the shafts I4 and 20 will mesh and the shaft I4 adjacent the bracket I3 will be urged in a counter-clockwise direction. As the shaft I4 is turned the other body of rubber-like material I1 will be stressed in torsional shear and offer resistance to turning of the shaft. The resultant cushioning action with the two bodies of resilient material stressed in torsional shear in `parallel will be stiffer than the cushioning action provided by one body. j

The body of rubber-like material I1 which is adjacent the Ibracket I3 may be preloaded in order that the engagement of the shaft I4 will have an appreciable effect on the cushioning action. Preloading may be effected by turning the lug 28 in a counter-clockwise direction as shown in Fig. 4 and holding the shaft at that position by means of the adjusting bolt 29 which is inserted in the channel member 3 I.

When the force required to turn the portion of shaft I4 adjacent the bracket I3 exceeds that required to preload the body of rubber-like material I1 adjacent the bracket I3 the lug will be turned in a counter-clockwise direction and leave the adjusting bolts 29 as shown in Fig. 5. Preloading may also be accomplished by moving the nut 21 on the threaded adjusting stud 26 to move the projection 24 in a clockwise direction while the lug is in engagement with the bolt 29.

The height of the wheel 31 with relation to the chassis may be controlled by turning the adjustment nut 21 which is threaded on the stud 26 connected to the adjusting ring 2| which is adjacent the longitudinal member II. By turning this adjusting nut 21 to urge the projection 24 in a clockwise direction as shown in Fig. 2, the arm 33 may be moved in a clockwise direction and the chassis raised with respect to the Wheel 31. Likewise -by adjusting the stud 26 to allow the yprojection 34 to move in a counter-clockwise direction toward the transverse member I2 the chassis may be lowered with respect to the wheel 31.

As the load upon the chassis is reduced the shafts I4 and 20 will tend to turn in a clockwise direction and the lug 28will engage the bolt 29 whereupon the two portions of the shaft and I4 will rotate relative to each other and the body of rubber-like material I1 which is adjacent the bracket I3 will not cushion the vehicle. The vehicle then will be suspended on one body of 4 rubber I1 and the deflection per unit weight will be great providing a soft springing action which is desirable for light loads.

A modified construction is shown in Fig. 6 and Fig. 7 in which one end of a shaft 40 is mounted in a flanged collar 38 which is mounted on the longitudinal member II. The other end of the shaft 40 ts in a slot in the bracket I3 and is held there by a strap member 39 mounted on the bracket by bolts 4I. The end portions of the shaft 40 are serrated and the abutting surfaces of the flanged collar 38 and the bracket slot have serrations for engagement with the shaft serrations to prevent rotation of the shaft 40 with respect to the chassis. A sleeve I6 is disposed about the shaft 40 and a body of rubberlike material I1 interposed between and mounted on the shaft and sleeve. An arm 33 connects sleeve I 6 with a wheel assembly 31 such as shown in Fig. l. An outer sleeve 42 is disposed about the sleeve I6 and an outer body of rubber-like material 43 is interposed between and mounted on the sleeve I6 and outer sleeve 42. A lug 44 is mounted on the outer sleeve 42 and a stop member 45 is mounted on the transverse member I2 of the chassis and disposed in a lost-motion connection such that rotation of the outer sleeve 42 may be restricted by the engagement of the lug 44 with the stop member 45.

In operation, the body of rubber-like material rI1 which is disposed between the shaft 40 and the sleeve I6 will be stressed in torsional shear and supply cushioning for the vehicle. Under heavy loads the sleeve I6 will be rotated in a counterclockwise direction an amount that will cause the lug 44 to engage the stop member 45. Then -upon additional counter-clockwise rotation the sleeve I6 caused by additional load upon the vehicle the outer body of rubber-like material 43 will be stressed in torsional shear also. The additional resistance to deflection set up by the outer body of rubber-like material 42 will cause a stiff springing action which is desirable with heavy loads. l

When the load is reduced the resilient properties of the bodies of rubber-like material I1 and `43 will urge the sleeve I6 in a clockwise direction and the outer sleeve 42 will be moved in a clockwise direction an amount suflicient to disengage the lug 44 and the stop member 45. Therefore, with a light load the vehicle will be cushioned only by the inner -body of rubber-like material I1 which will provide a soft cushioning action.

Variations in the cushioning properties of this spring assembly may be obtained by using a more resilient material or a less resilient material in the body of rubber-like material. Also the angle through which the outer sleeve 42 turns before it engages the stop member 45 may be changed by removing the shaft 4I] from the flanged collar 38 by removing the opposite end of the shaft 40 from the slot in the bracket I3. Then if the shaft 40 is turned in a counter-clockwise direction as seen in Fig. 7 and reinserted in the collar 38 and bracket I3 the angle through which the sleeve 42 turns before engagement will be decreased. Conversely if the shaft 40 is turned clockwise as seen lin Fig. 7 and reinserted the angle through which the sleeve turns before engagement will be increased.

Another modication is shown in Fig. 8. A flanged collar 38 is mounted on the longitudinal member and a shaft 50 of the spring assembly is mounted rotatably in the flanged collar. The shaft 50 is disposed in a position transverse of the chassis and has a pair of sleeves I6, I6 mounted axially thereabout with bodies of rubber-like material I1, I1 interposed between the shaft 5I! and the sleeves. One sleeve IS is mounted xedly on the transverse member I2 of the chassis and the other sleeve I6 is connected to the wheel assembly by an arm 33. A lug 46 is mounted on the shaft 5|] and a projection 41 on the sleeve I6 which is not xedly mounted on the transverse member I2 are disposed in a lost-motion connection such that relative rotary movement of the movable sleeve I6 with respect to the shaft 50 is limited by the engagement of the lug 46 and the projection 41.

In operation, as the arm 33 is moved relative to the chassis by an increase in the load on the chassis the sleeve I6 to which the arm 33 is attached will be rotated causing the body of rubber-like material I1 and the shaft di) to rotate. Under a light load both the bodies of rubberlike material I1, I1 will be stressed in torsional shear in series and the vehicle will be provided with soft springing action. As the load is increased, the bodies of rubber-like material I1, I1 will be stressed and deflect to such an extent that the stop projection 41 will engage the lug 46 causing the body of rubber-like material I1 adjacent the sleeve I6 to provide all the cushioning for the wheel suspension assembly 31 providing a stiff springing action. v

The characteristics of this spring assembly may also be changed by substituting more or less resilient material for the bodies of rubber-like material I1, I1. The modification shown in Fig. 8 is for the suspension of one wheel of the vehicle and the suspension for the other wheels may be similarly constructed.

Variations may be made without departing from the invention as it is defined in the following claims.

I claim:

1. A spring suspension comprising a structure, a shaft journaled in said structure for' relative rotation thereto, a pair of axially spaced-apart cylindrical members about said shaft, one of said cylindrical members being mounted on said structure, a radially extending arm mounted on the other of said cylindrical members, bodies of resilient rubber-like material mounted between said shaft and said members for resisting relative rotation of said shaft and said members in cylindrical shear for cushioning rotative movement of said arm relative to said structure, a lug mounted on said shaft and projecting radially therefrom and a stop element projecting from the member upon which said arm is mounted into lost-motion relation with respect to the lug for twisting both said bodies during the rotative movement of said arm relative to said structure through the lostmotion range and for twisting only the body having the cylindrical member mounted on said structure during the rotative movement of said arm relative to said structure after engagement of said lug and said stop element for increasing the resistance to rotative movement of said arm relative to said structure.

2. A spring assembly comprising a structure, a shaft member disposed for rotation relative to said structure, a pair of axially spaced-apart sleeve members about said shaft, bodies of resilient rubber-like material mounted between said sleeve members and said shaft member, one of said sleeve members being mounted on said structure, lost-motion connecting means between the other of said sleeve members and said shaft member comprising a radially extending lug mounted on said shaft member and an axially projecting element disposed non-rotatively with respect to the other of Asaid sleeve members in angularly spaced lost-motion relation to said lug in the unstressed condition of the spring assembly and engageable therewith upon relative rotative movement of said shaft member and said structure for limiting the twisting of one of said bodies of resilient rubber-like material while permitting continued relative rotation of said shaft and said structure and continued twisting of the other of said bodies of resilient rubber-like material.

3. A spring suspension comprising a plurality of sleeves disposed in axially spaced relationA about a shaft providing pairs of radially opposed surfaces, a radially extending arm mounted on one of said sleeves, bodies of resilient rubberlike material mounted between the opposed surfaces of said pairs of radially opposed surfaces for cushioning rotative movement of said arm about the axis of said shaft, a lug mounted on said shaft and another engaging element projecting from the sleeve on which said arm is mounted into angularly spaced lost-motion relation with respect to the lug in the unstressed condition of the spring and engageable therewith upon rotative movement of said ,arm through the angle of the lost-motion range beyond for twisting said bodies together while said arm is turned through one of the ranges and for twisting one of said bodies relative to the other while said arm is turned through the other of the ranges.

ALVIN Si. KROTZ.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,069,270 Piron Feb. 2, 1937 2,167,508 Herold July 25, 1939 2,216,455 Piron Oct. 1, 1940 2,270,572 Woolson et al Jan. 20, 1942 2,393,183 Parker Jan. 15, 1946 2,409,501 Krotz Oct. 15, 1946 2,477,187 Lanchner July 26, 1949 

